Apparatus for removing paint



April 17, 1934. c. H. KENNEY APPARATUS FOR REMOVING PAINT Filed Dec. 5, 1930 so 0 0 o o m 6 o o o O o Q 7 R m Q /& Q N N g Q @MN w run )Qm, o Q Q 4: S g R Rh \hwwh Patented Apr. 17, 1934 arraaa'rus roa REMOVING PAINT Charles H. Kenney, New London, Conn., assignor to Edward F. Woods, Boston, Mass.

Application December 5, 1930, Serial No. 500,410

9 Claims.

This invention relates to'the art of removing finishes or coatings such as paint and to improved means for removing coatings of this character.

In some aspects the invention relates to means for removing a coat of paint, for example, by applying heat thereto to cause the paint to soften or to blister preferably at points just in advance of a scraping device, so that the latter may be readily effective for scraping or peeling oil the loosened coating. While it is customary to employ an electrical or similar halting unit for softening and loosening a coating to' be removed, devices of this character as heretofore provided have been rather inefllcient and quite unsatisfactory due largely to the relatively low heat transfer capacity for the heating apparatus. Frequently the coatings to be removed are exposed in the open air or to air currents which carry away heat very rapidly. Moreover, it will be apparent that when heat is applied only by radiation or even by conduction the process is necessarily quite slow and tedious unless relatively large heating currents are employed, in which event the cost of the power consumed is usually prohibitiv Objects of the invention are to improve the efficiency of apparatus of the class referred to by providing for increasing the heat transfer per unit of area in the immediate vicinity of the scraping device; to provide for obtaining this increased heat transfer capacity from apparatus which is economical of power and therefore inexpensive to operate; to provide for applying heat in a manner to effect loosening of paint to be removed as well as to avoid immediate cooling of paint being removed, and thereby toexpedite the process of removal; to provide for controlling temperature so as to avoid damage to a surface from which a coating is being removed: to provide a hand tool embodying these features; to provide apparatus of this general class of rugged, durable and yet simple and eiilcient construction consisting of relatively few parts which are inexpensive to manufacture and to assemble; and also to provide apparatus of the class described having an improved construction and relative arrangement of parts.

In the drawing: v

Fig. 1 is a central longitudinal section through a hand tool for removing paint;

Fig. 1;

Fig. 3 is a bottom plan view of the nozzle shown in Figs. 1 and 2; and

Fig. 4 is a section along the line 44 of Fig. 1. In the apparatus selected for illustration a cut- Fig. 2 is an end elevation of the nozzle shown in (Cl. 2l9-29) ter or scraper 10 is mounted upon the end portion of a frame here shown in the form of hollow casing or housing comprising a cylinder 11 having circumferentially extending exterior corrugations 12 providing a large heat radiating surface. An end piece 13 has threaded engagement with one end of the cylinder and converges into the form of a nozzle 14 having a slot 16 extending across the end thereof to form a relatively flat port arranged to direct the major portion of the blast issuing from the nozzle across the sharpened or beveled edge portion 17 of the cutter 10. On the under side of the nozzle holes 18 are arranged in transversely extending rows for directing other portions of the blast across the path of material removed by the effective edge 17 of the cutter. As shown more clearly in Fig. 2 this cutter is in the form of a substantially U-shaped strip having the base of the U substantially flat to form a good bearing upon a surface from which paint is to be removed and the side arms 19 and 21 of the U embrace the sides of the nozzle and are rigidly secured thereto in any approved manner as by means of rivets 22, 23.

To provide for heating a blast passing through the casing cylinder 11 a heating unit, indicated generally at 24, is disposed within the cylinder and spaced from the inner side walls thereof, preferably being supported in this spaced relation by a suitable number of attaching screws 26. This heating unit comprises a heating element such as a resistance wire or the like 27 which is encased in refractory material 28. The heating element preferably extends from a terminal 29 at one end of the unit in a substantially helical path to the other end of the unit and returns to the terminal 31 in a similar path. In the construction of this heating unit the body of refractory .material 28 is formed with a hollow core 33 having a closed end 34. Preferably this core piece is formed of suitable refractory material and has formed in its exterior surface a double thread providing a helical path for the heating element. This heating element follows one of the threads from the closed end of the core to the open end thereof and returns through the other thread to the closed end of the core. After the heating element is thus laid in the grooves it is covered over with suitable refractory material, thereby completely encasing this element. The end piece 13 has a transversely disposed wall 36 which is bored to provide a hearing or support for a tube 37 which extends axially within the heating unit to a point spaced somewhat from the closed end thereof.

The end of the cylinder 11 opposite the nozzle 14 diverges as indicated at 38 and is connected to a cylindrical casing wall 39 which encloses a rotary compressor 41. A driving motor 42 is enclosed in a casing 43 aflixed to the casing 39 and a handle 44. is attached to the casing 43. The shaft 46'of the motor is journalled in bearings carried by the end walls of the casings 43v and 39 and is rigidly connected to the rotor 47 of the compressor. This rotor is provided with blade receiving slots 48 in which blades 49 operate in a manner well understood in this art. The compressor casing is formed with an inlet chamber 51 to which air is admitted through a plurality of circumferentially spaced ports 52 and from which air passes through a port 53 to the compression chamber 54 of the compressor. Compressed air is delivered by the compressor through the port 56 to the chamber 57 having a port 58 affording communication with the interior of the cylindrical casing member 11. The armature shaft 46 of the motor also carries a fan 59 and the overlap ping portions of the casings 39 and 43 are provided with circumferentially spaced inlet ports 61 while the end wall of the casing 43 is provided with a circular row ofoutlet ports 62.

Electrical energy for operating the device is supplied through wires 63 and 64 which may be enclosed in a conduit or insulator (not shown) extending upwardly through the base of the handie 44. The wire 63 is connected to the terminal 67 of spring switch 68 and a wire 65 extends between the terminal 69 of a spring switch 71 and the wire 63. A cam lever 72 is pivotally mounted on the inner side of the handle in a position to depress the spring switch 68 against the terminal 73. In a like manner a cam lever 74 is mounted to pivot on the outer side of the handle in a position to be operable for depressing the spring switch 71 against the terminal piece 76. A wire 77 extends between the terminal 76 and the terminal 29 of the heating element 27. A wire 78 connected to the other terminal 31 of the heating element is connected to the wire 64 which extends to the terminal 82 of'the motor. The otherterminal 81 of the motor is connected by a wire 79 to the terminal 73 of spring switch 68.

In using the device for removing paint or like coatings from surfaces an operator grips the handle 44 and the body portion of the cylinder 11 which may be provided with a suitable handle if desired so that the cutter 10 may conveniently be moved along the surface from which a coating is to be removed. It will be observed that the cam levers 72 and 74 are disposed in a position to be readily accessible by the hand gripping handle 44, and while it is contemplated that in some instances these cam levers may be mounted upon other adjacent portionsof the body as on the motor casing 43, it is-preferre'd that these controls be mounted upon the upper portion ofthe handle 44. substantially as shown. on closing the switch 71 current is supplied to the heating element and on closing the switch 72'the motor 42 is set in operation thereby actuating the compressor which delivers the blast of air through the port58 into the enlarged end 38 of the cylinder casing member 11.

Due tothe arrangement of the heating unit 24 in spaced relation within the cylinder it will be seen that this blast is delivered past the heating "unit in heat transfer relation therewith in a plurality of passes. the port 58 passes first about the exterior side walls of the heating unit to the open end thereof and then from this open end along the inner side walls formed by the refractory material 28 to the closed end 34 of this heating unit from which the blast is directed in a final pass through the tube 37 into the nozzle 14. From this nozzle the major portion of the blast issuesthrough the fiat port 16 and is directed across the effective edge 17 of the cutter, preferably somewhat in advance of this edge so as to be effective for softening or blistering paint to be removed. The ports 18- arearranged to deliver other portions of the blast across the path of paint being removed so as to prevent immediate hardening of the paint and thereby causing the same to peel off. During the time the motor is in operation the fan 59 draws air through the inlet ports 61 and sets up a cooling current through the motor and out through the ports 62 of the motor casing. The heating unit is preferably so proportioned and designed as to heat the blast sufficiently to maintain this blast at a temperature between 400 and 600 F. as it issues from the nozzle. The

and equivalents which fall within the scope of.

the appended claims. I

I claim:

l. A device of the class described, comprising a frame, a scraper carried by the frame, a heating element supported by the frame and disposed substantially in a helicalpath, and means for directing a blast of air axially of the heating element in heat transfer relation therewithtoward the scraper for softening paint to be removed.

2. A device of the class described, comprising a frame, a scraper carried by the frame, a heating element supported by the frame and disposed substantiallyin a helical path, and means for directing a blast of air about the heating element in a plurality of passes in heat transfer relation therewith and finally toward the scraper for softening paint to be removed.

3. A device of the class described, comprising a frame, a scraper carried by the frame,a heating element supported by the frame and disposed substantially in a helical path, and means for directing a blast of air about the heating element and in a plurality of passes within the heating element in heat transfer relation therewith and finally toward the scraper for softening paint to be removed.

4. A device of the class described, comprising a frame, a scraper carried by the frame, a heat- 5. A device of the class described comprising a cylinder having exterior corrugations providing Thus the blast issuing from a large-heat radiating surface, a heating element disposed substantially in a helical path within the cylinder, a scraper supported from one end ing element supported by the frame and disposed of the cylinder'and means for directing a blast of air through the cylinder and in heat transfer relation with the heating element and toward the scraper for softening paint to be removed.

6. A device of the class described comprising a cylinder, a heating element disposed substantially in a helical path within the cylinder. a scraper supported from one end of the cylinder, a compressor connected to the other end of the cylinder and arranged to deliver a blast of air thereto, and means for directing the air blast axially of the cylinder in a plurality of passes in heat transfer relation with the heating element and finally toward the scraper for softening paint to be removed.

' '1. A device of the class described comprising a cylinder, a heating element disposed substantially in a helical path within the cylinder, a scraper supported from one end of the cylinder, a motor-compressor unit connected to the other end of the frame with the compressor arranged to deliver a blast of air into the cylinder, and means .for directing the air blast in a tortuous course about the heating element and toward the scraper for softening paint to be removed.

8'. A device of the class described comprising a cylinder, a heating element disposed substantially in a helical path within the cylinder, a scraper supported from one end of the cylinder, a motor-compressor unit connected to the other end of the frame with the compressor arranged to deliver a blast of air into the cylinder, means for directing the air blast in a tortuous course about the heating element and toward the scrap for softening paint to be removed, and means for producing-a current of cooling air in a direction away from the compressor and through the motor 9. A device of the class described, comprising a hollow casing, a heating unit disposed within the casing, a scraper supported from an end of the casing, means for delivering a blast of air through the casing in heat transfer relation with the heating unit and toward the scraper, means for directing the major portion of the blast substantially across the effective portion of the scraper for softening paint to be removed, and means for causing other portions of the blast to be directed into the path of paint being removed to prevent immediate cooling and hardening thereof.

CHARLES H. KENNEY.

ill 

